1. Field of the Invention
This invention relates to apparatus for stacking material and, more particularly, to apparatus for stacking laundry pieces into a stack by count.
2. Description of the Prior Art
Devices for stacking material have long been available in the prior art. For example, U.S. Pat. No. 25,524, issued in 1859, describes the concept of stacking printed sheets by means of a pivoted double conveyor wherein sheets entering into the printing press face down are piled face up in sequence.
U.S. Pat. No. 2,686,673 discloses apparatus for stacking flexible sheet material, such as hides or skins, into a pile, the apparatus having the capability of varying the form of stack provided. A pivoted double conveyor is also provided to deliver the sheet material to the pile. Electrical means are provided for detecting the leading and trailing edges of each sheet which in turn controls the movement of the double conveyor.
U.S. Pat. No. 2,250,572 discloses a machine for tearing material from a long web of material to form sheets and an oscillating pinch belt conveyor for delivering the torn sheets to a stack. The belt conveyor is caused to run faster than the speed at which the web is delivered through the tearing rolls so as to prevent slack in the material when it is engaged by the tearing roll.
U.S. Pat. No. 2,737,390 discloses an automatic hide or skin stacking device which includes means for delivering a workpiece on a workpiece receiving means and, in particular, wherein the discharge end of a pivoted double conveyor is arranged to oscillate in an arc over the work deposit zone such that a workpiece is draped over the receiving means. A circuit sensitive to the length of each workpiece is provided such that the center thereof is draped over the receiving means at the same position.
U.S. Pat. No. 2,743,924 discloses an improved control system for use in a machine of the type described in U.S. Pat. No. 2,737,390.
U.S. Pat. No. 2,766,045 discloses means for detecting the leading and trailing edges of a workpiece in a machine of the type described in U.S. Pat. No. 2,737,390 and further includes means intermediate the trailing and leading edge detector means to prevent false detection of intermediate edges of irregularly shaped workpieces.
U.S. Pat. No. 2,855,089 disclosed an apparatus for unloading a conveyor wherein a light source and photoelectric cell are used to detect the leading edge of a workpiece.
The aforementioned stacking apparatus involves various techniques for stacking printed sheets, skins or hides on a work receiving means at a work deposit zone. However, no means are described for limiting stack size or for automatically conveying the stack away from the deposit zone to allow the formation of additional stacks.
The inability of prior art stacking apparatus to automatically form a plurality of workpiece stacks makes their use in commercial laundries inefficient from a cost standpoint, since manual labor would still be required to continually remove and stack the laundry as it is formed. In particular, for commercial laundries, it would be desirable if a laundry piece stacking apparatus could be provided wherein pressed laundry pieces are stacked substantially smooth and wrinkle-free, with the edges of the stack aligned, with the alignment being maintained as the stack is conveyed towards a remote station after a predetermined number of laundry pieces have been placed in the stack and wherein additional stacks of predetermined size are continually being formed and similarly conveyed to the remote station.